What is Superstructure?
Superstructure is a term used to describe the structural elements of a building which are above the foundation, or ground level.
Typically constructed from reinforced concrete or steel elements, a superstructure creates the basis of a building.
You may hear it being referred to as a 'frame' on site.
It provides support and shelter, allocates spaces and greatly impacts the aesthetic of a building (even though it can't necessarily be seen).
Technically the 'envelope' of the building which includes windows, doors and the 'finishes' which include internal walls and finishes form part of the superstructure. However, these will have their own posts.
Elements of superstructure:
The following elements could form part of the superstructure on the project you are working on. They can be used in combination and are based on what the structural engineer, architect and principal contractor feel suit the job best:
Structural Slab - Typically made from reinforced concrete. This is the horizontal base a floor sits on. It transfers the loading from the building into the foundations below.
Reinforced concrete slab being poured
If the building is designed with a steel frame, the slabs have a slightly different build up. Either:
A corrugated metal deck is installed between the steel elements and then a mesh is cast into a structural topping on the deck to form the slab.
View from under a steel frame showing the corrugated metal deck which forms the floor
OR: precast concrete planks are placed between the steel beams and a structural topping with a cast is cast on top of them to form the slab.
A precast concrete slab element (or plank) being lifted into position
Columns - structural elements that are designed to support vertical loads and transfer them to a building's foundation or another structural system.
Running between floors their function is to transfer the loadings from each floor down to the foundations.
A reinforced concrete frame
If the building's superstructure was constructed from steel the columns would also be steel.
Beams - horizontal structural elements that are designed to support loads and transfer them to vertical columns or other elements within a building.
A series of concrete beams supporting a floor slab
Same concept as columns - in steel framed buildings beams would be constructed with steel.
Walls - not to be mistaken for internal walls. Most of the time structural walls are not visible once the building is finished.
Most common form of wall which is part of a building's superstructure is a shear wall. These are used with both reinforced concrete and steel buildings.
Shear walls are designed to resist lateral (horizontal) forces, such as wind or seismic forces. They prevent a building from swaying or collapsing during these events.
Shear walls are typically made of concrete or reinforced masonry and are strategically placed throughout a building. You may find these form the core walls which stabilise the structure.
Definitions
Reinforced concrete - concrete with embedded steel inside to increase strength and durability
Steel frame - refers to a structural system where the primary load-bearing elements are made of steel
Mesh - network of interconnected steel reinforcement typically arranged in a pattern of squares or rectangles. Different to reinforced concrete bars which are tied on site as mesh is bound together off site and delivered in sheets
Structural topping
Posts to Follow
We plan to go into more details on Superstructure and add sections on:
Design
Types of Substructure
Logistics
Temporary Works
Build Sequence
Health, Safety & Environment
Quality
Programme
Commercial
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